1. Field of the Invention
The present invention relates generally to methods of forming elements with specific shapes, and more specifically to methods of forming elements having a curved free surface on an end of a supporting member.
2. Technical Background
In optical communication systems, messages are transmitted by electromagnetic carrier waves at optical frequencies that are generated by such sources as lasers and light-emitting diodes. There is interest in such optical communication systems because they offer several advantages over conventional communication systems. Optical communications systems are described in detail in Hecht, J. Understanding Fiber Optics, 3rd Ed., Prentice Hall, Upper Saddle River, N.J., 1999, as well as in European Patent Application Publications EP 0 398 991 and EP 0 474 692.
Optical fibers are conventionally used to transmit signals in optical communications systems. Optical fibers in which a single optical mode is allowed for the wavelength of the optical signal are generally the most desirable for use in optical communications systems. Single mode fibers tend to have very small core diameters, on the order of 5–10 μm. Coupling optical radiation from a source such as a laser or a light emitting diode into the core of a single mode fiber is difficult. The optical signal emerging from the end of an optical fiber tends to diverge, making it problematic to use the emerging optical signal in a free-space device. To solve these problems, a lensing system is often used at the end of the optical fibers.
Lensing systems often include an optical fiber with curved elements built directly on the end of the fiber. Due to the small size of the end of the optical fiber, conventional manufacturing techniques are not appropriate for the formation of the curved element. Existing methods for providing curved elements on the ends of optical fibers use techniques such as gray-scale photolithography and glass melting to provide curvature. Glass melting methods are described in International Patent Application Publication Number WO 01/71403. In these methods, a molten drop of glass is formed on the end of an optical fiber, and is allowed to harden by cooling, forming a ball lens on the end of the fiber. However, these methods can be difficult to perform, and may not yield elements with the curvature desired for a specific application.